Date:	Fri, 30 Jan 2015 11:40:12 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	"Luck, Tony" <tony.luck@...el.com>
Cc:	linux-edac <linux-edac@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] einj: Documentation text corrections and streamlining

On Thu, Jan 29, 2015 at 07:40:17PM +0000, Luck, Tony wrote:
> How about a paragraph telling people how to check whether their platform supports

I took your text and massaged it into the doc, diff ontop:

---
diff --git a/Documentation/acpi/apei/einj.txt b/Documentation/acpi/apei/einj.txt
index 026e8913339c..e550c8b98139 100644
--- a/Documentation/acpi/apei/einj.txt
+++ b/Documentation/acpi/apei/einj.txt
@@ -4,6 +4,24 @@
 EINJ provides a hardware error injection mechanism. It is very useful
 for debugging and testing APEI and RAS features in general.
 
+You need to check whether your BIOS supports EINJ first. For that, look
+for early boot messages similar to this one:
+
+ACPI: EINJ 0x000000007370A000 000150 (v01 INTEL           00000001 INTL 00000001)
+
+which shows that the BIOS is exposing an EINJ table - it is the
+mechanism through which the injection is done.
+
+Alternatively, look in /sys/firmware/acpi/tables for an "EINJ" file,
+which is a different representation of the same thing.
+
+It doesn't necessarily mean that EINJ is not supported if those above
+don't exist: before you give up, go into BIOS setup to see if the BIOS
+has an option to enable error injection. Look for something called WHEA
+or similar. Often, you need to enable an ACPI5 support option prior, in
+order to see the APEI,EINJ,... functionality supported and exposed by
+the BIOS menu.
+
 To use EINJ, make sure the following are options enabled in your kernel
 configuration:
 
@@ -100,18 +118,29 @@ for memory injections to be specified by the param1 and param2 files in
 apei/einj.
 
 BIOS versions based on the ACPI 5.0 specification have more control over
-the target of the injection. For processor-related errors (type 0x1,
-0x2 and 0x4) the APIC ID of the target should be provided using the
-param1 file in apei/einj. For memory errors (type 0x8, 0x10 and 0x20)
-the address is set using param1 with a mask in param2 (0x0 is equivalent
-to all ones). For PCI express errors (type 0x40, 0x80 and 0x100) the
-segment, bus, device and function are specified using param1:
+the target of the injection. For processor-related errors (type 0x1, 0x2
+and 0x4), you can set flags to 0x3 (param3 for bit 0, and param1 and
+param2 for bit 1) so that you have more information added to the error
+signature being injected. The actual data passed is this:
+
+	memory_address = param1;
+	memory_address_range = param2;
+	apicid = param3;
+	pcie_sbdf = param4;
+
+For memory errors (type 0x8, 0x10 and 0x20) the address is set using
+param1 with a mask in param2 (0x0 is equivalent to all ones). For PCI
+express errors (type 0x40, 0x80 and 0x100) the segment, bus, device and
+function are specified using param1:
 
          31     24 23    16 15    11 10      8  7        0
 	+-------------------------------------------------+
 	| segment |   bus  | device | function | reserved |
 	+-------------------------------------------------+
 
+Anyway, you get the idea, if there's doubt just take a look at the code
+in drivers/acpi/apei/einj.c.
+
 An ACPI 5.0 BIOS may also allow vendor-specific errors to be injected.
 In this case a file named vendor will contain identifying information
 from the BIOS that hopefully will allow an application wishing to use

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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